var _w = window,
    _b = document.body, //返回html dom中的body节点 即<body>
    _d = document.documentElement; //返回html dom中的root 节点 即<html>

// random helper
var random = function () {
    if (arguments.length === 1) // only 1 argument
    {
        if (Array.isArray(arguments[0])) // extract index from array
        {
            var index = Math.round(random(0, arguments[0].length - 1));
            return arguments[0][index];
        }
        return random(0, arguments[0]); // assume numeric
    } else
    if (arguments.length === 2) // two arguments range
    {
        return Math.random() * (arguments[1] - arguments[0]) + arguments[0];
    }
    return 0; // default
};

// screen helper
var screenInfo = function (e) {
    var width = Math.max(0, _w.innerWidth || _d.clientWidth || _b.clientWidth || 0),
        height = Math.max(0, _w.innerHeight || _d.clientHeight || _b.clientHeight || 0),
        scrollx = Math.max(0, _w.pageXOffset || _d.scrollLeft || _b.scrollLeft || 0) - (_d.clientLeft || 0),
        scrolly = Math.max(0, _w.pageYOffset || _d.scrollTop || _b.scrollTop || 0) - (_d.clientTop || 0);

    return {
        width: width,
        height: height,
        ratio: width / height,
        centerx: width / 2,
        centery: height / 2,
        scrollx: scrollx,
        scrolly: scrolly
    };

};

// mouse/input helper
var mouseInfo = function (e) {
    var screen = screenInfo(e),
        mousex = e ? Math.max(0, e.pageX || e.clientX || 0) : 0,
        mousey = e ? Math.max(0, e.pageY || e.clientY || 0) : 0;

    return {
        mousex: mousex,
        mousey: mousey,
        centerx: mousex - screen.width / 2,
        centery: mousey - screen.height / 2
    };

};

// point object
var Point = function (x, y) {
    this.x = 0;
    this.y = 0;
    this.set(x, y);
};
Point.prototype = {
    constructor: Point,

    set: function (x, y) {
        this.x = x || 0;
        this.y = y || 0;
    },
    copy: function (point) {
        this.x = point.x || 0;
        this.y = point.y || 0;
        return this;
    },
    multiply: function (x, y) {
        this.x *= x || 1;
        this.y *= y || 1;
        return this;
    },
    divide: function (x, y) {
        this.x /= x || 1;
        this.y /= y || 1;
        return this;
    },
    add: function (x, y) {
        this.x += x || 0;
        this.y += y || 0;
        return this;
    },
    subtract: function (x, y) {
        this.x -= x || 0;
        this.y -= y || 0;
        return this;
    },
    clampX: function (min, max) {
        this.x = Math.max(min, Math.min(this.x, max));
        return this;
    },
    clampY: function (min, max) {
        this.y = Math.max(min, Math.min(this.y, max));
        return this;
    },
    flipX: function () {
        this.x *= -1;
        return this;
    },
    flipY: function () {
        this.y *= -1;
        return this;
    }
};


// class constructor
var Factory = function (options, id) {
    this._targetId = id;
    this._canvas = null;
    this._context = null;
    this._sto = null;
    this._width = 0;
    this._height = 0;
    this._scroll = 0;
    this._ribbons = [];
    this._options = {
        // ribbon color HSL saturation amount
        colorSaturation: "80%",
        // ribbon color HSL brightness amount
        colorBrightness: "60%",
        // ribbon color opacity amount
        colorAlpha: 0.65,
        // how fast to cycle through colors in the HSL color space
        colorCycleSpeed: 6,
        // where to start from on the Y axis on each side (top|min, middle|center, bottom|max, random)
        verticalPosition: "center",
        // how fast to get to the other side of the screen
        horizontalSpeed: 200,
        // how many ribbons to keep on screen at any given time
        ribbonCount: 3,
        // add stroke along with ribbon fill colors
        strokeSize: 0,
        // move ribbons vertically by a factor on page scroll
        parallaxAmount: -0.5,
        // add animation effect to each ribbon section over time
        animateSections: true
    };

    this._onDraw = this._onDraw.bind(this);
    this._onResize = this._onResize.bind(this);
    this._onScroll = this._onScroll.bind(this);
    this.setOptions(options);
    this.init();
};

// class prototype
Factory.prototype = {
    constructor: Factory,

    // Set and merge local options
    setOptions: function (options) {
        if (typeof options === "object") {
            for (var key in options) {
                if (options.hasOwnProperty(key)) {
                    this._options[key] = options[key];
                }
            }
        }
    },

    // Initialize the ribbons effect
    init: function () {
        try {
            this._canvas = document.createElement("canvas");
            this._canvas.style["display"] = "block";
            this._canvas.style["position"] = "fixed";
            this._canvas.style["margin"] = "0";
            this._canvas.style["padding"] = "0";
            this._canvas.style["border"] = "0";
            this._canvas.style["outline"] = "0";
            this._canvas.style["left"] = "0";
            this._canvas.style["top"] = "0";
            this._canvas.style["width"] = "100%";
            this._canvas.style["height"] = "100%";
            this._canvas.style["z-index"] = "-1";
            // this._canvas.style["background-color"]="#1f1f1f";
            this._canvas.id = "bgCanvas";
            this._onResize();

            this._context = this._canvas.getContext("2d");
            this._context.clearRect(0, 0, this._width, this._height);
            this._context.globalAlpha = this._options.colorAlpha;

            window.addEventListener("resize", this._onResize);
            window.addEventListener("scroll", this._onScroll);
            document.getElementById(this._targetId).appendChild(this._canvas);
        } catch (e) {
            console.warn("Canvas Context Error: " + e.toString());
            return;
        }
        this._onDraw();
    },

    // Create a new random ribbon and to the list
    addRibbon: function () {
        // movement data
        var dir = Math.round(random(1, 9)) > 5 ? "right" : "left",
            stop = 1000,
            hide = 200,
            min = 0 - hide,
            max = this._width + hide,
            movex = 0,
            movey = 0,
            startx = dir === "right" ? min : max,
            starty = Math.round(random(0, this._height));

        // asjust starty based on options
        if (/^(top|min)$/i.test(this._options.verticalPosition)) {
            starty = 0 + hide;
        } else
        if (/^(middle|center)$/i.test(this._options.verticalPosition)) {
            starty = this._height / 2;
        } else
        if (/^(bottom|max)$/i.test(this._options.verticalPosition)) {
            starty = this._height - hide;
        }

        // ribbon sections data
        var ribbon = [],
            point1 = new Point(startx, starty),
            point2 = new Point(startx, starty),
            point3 = null,
            color = Math.round(random(0, 360)),
            delay = 0;

        // buils ribbon sections
        while (true) {
            if (stop <= 0) break;
            stop--;

            movex = Math.round((Math.random() * 1 - 0.2) * this._options.horizontalSpeed);
            movey = Math.round((Math.random() * 1 - 0.5) * (this._height * 0.25));

            point3 = new Point();
            point3.copy(point2);

            if (dir === "right") {
                point3.add(movex, movey);
                if (point2.x >= max) break;
            } else
            if (dir === "left") {
                point3.subtract(movex, movey);
                if (point2.x <= min) break;
            }
            // point3.clampY( 0, this._height );

            ribbon.push({ // single ribbon section
                point1: new Point(point1.x, point1.y),
                point2: new Point(point2.x, point2.y),
                point3: point3,
                color: color,
                delay: delay,
                dir: dir,
                alpha: 0,
                phase: 0
            });


            point1.copy(point2);
            point2.copy(point3);

            delay += 4;
            color += this._options.colorCycleSpeed;
        }
        this._ribbons.push(ribbon);
    },

    // Draw single section
    _drawRibbonSection: function (section) {
        if (section) {
            if (section.phase >= 1 && section.alpha <= 0) {
                return true; // done
            }
            if (section.delay <= 0) {
                section.phase += 0.02;
                section.alpha = Math.sin(section.phase) * 1;
                section.alpha = section.alpha <= 0 ? 0 : section.alpha;
                section.alpha = section.alpha >= 1 ? 1 : section.alpha;

                if (this._options.animateSections) {
                    var mod = Math.sin(1 + section.phase * Math.PI / 2) * 0.1;

                    if (section.dir === "right") {
                        section.point1.add(mod, 0);
                        section.point2.add(mod, 0);
                        section.point3.add(mod, 0);
                    } else {
                        section.point1.subtract(mod, 0);
                        section.point2.subtract(mod, 0);
                        section.point3.subtract(mod, 0);
                    }
                    section.point1.add(0, mod);
                    section.point2.add(0, mod);
                    section.point3.add(0, mod);
                }
            } else {
                section.delay -= 0.5;
            }

            var s = this._options.colorSaturation,
                l = this._options.colorBrightness,
                c = "hsla(" + section.color + ", " + s + ", " + l + ", " + section.alpha + " )";

            this._context.save();

            if (this._options.parallaxAmount !== 0) {
                this._context.translate(0, this._scroll * this._options.parallaxAmount);
            }
            this._context.beginPath();
            this._context.moveTo(section.point1.x, section.point1.y);
            this._context.lineTo(section.point2.x, section.point2.y);
            this._context.lineTo(section.point3.x, section.point3.y);
            this._context.fillStyle = c;
            this._context.fill();

            if (this._options.strokeSize > 0) {
                this._context.lineWidth = this._options.strokeSize;
                this._context.strokeStyle = c;
                this._context.lineCap = "round";
                this._context.stroke();
            }
            this._context.restore();
        }
        return false; // not done yet
    },

    // Draw ribbons
    _onDraw: function () {
        // cleanup on ribbons list to rtemoved finished ribbons
        for (var i = 0, t = this._ribbons.length; i < t; ++i) {
            if (!this._ribbons[i]) {
                this._ribbons.splice(i, 1);
            }
        }

        // draw new ribbons 
        this._context.clearRect(0, 0, this._width, this._height);

        for (var a = 0; a < this._ribbons.length; ++a) // single ribbon
        {
            var ribbon = this._ribbons[a],
                numSections = ribbon.length,
                numDone = 0;

            for (var b = 0; b < numSections; ++b) // ribbon section
            {
                if (this._drawRibbonSection(ribbon[b])) {
                    numDone++; // section done
                }
            }
            if (numDone >= numSections) // ribbon done
            {
                this._ribbons[a] = null;
            }
        }
        // maintain optional number of ribbons on canvas
        if (this._ribbons.length < this._options.ribbonCount) {
            this.addRibbon();
        }
        requestAnimationFrame(this._onDraw);
    },

    // Update container size info
    _onResize: function (e) {
        var screen = screenInfo(e);
        this._width = screen.width;
        this._height = screen.height;

        if (this._canvas) {
            this._canvas.width = this._width;
            this._canvas.height = this._height;

            if (this._context) {
                this._context.globalAlpha = this._options.colorAlpha;
            }
        }
    },

    // Update container size info
    _onScroll: function (e) {
        var screen = screenInfo(e);
        this._scroll = screen.scrolly;
    }
};

export default Factory